1. Field of the Invention
The present invention relates to a method and an apparatus for the remote determination of three-dimensional shapes of dental objects, such as teeth, casts of teeth and models of teeth.
2. Description of the Background Art
A current trend in dental care is a desired to stop performing restoration procedures, involving shaping materials such as amalgam and plastic, directly in the mouth. Instead, the trend is to develop or shape materials outside of the mouth. Such shaping outside the mouth can occur by die casting, spark machining, abrasive machining or similar acts.
In order to shape materials outside the mouth, or for that matter inside the mouth, it is important to determine an accurate three-dimensional shape of the dental object being replaced or restored. By determining the shape of a dental object, such as a drilled-out tooth, in three dimensions, a suitably adapted restoration insert, such as a filling, can be produced to fit the object. There is also an increased need for the three dimensional shape of the dental object to be made more accurately and remotely.
An arrangement for producing dental inserts that uses a mechanical means to transfer the shape from an impression of the tooth to a machining tool is known. The accuracy of the shape of such an insert is, however, often too low to achieve a reliable repair.
U.S. Pat. No. 4,964,770 shows an arrangement for producing an artificial tooth where the stump of the tooth is illuminated by a strip of wide light and where a camera is arranged to scan-in the illuminated stump of the tooth. When the scanned-in information is processed, the intensity of light at the lines and along their lengths constitutes an important factor for determining the shape of the stump of the tooth.
Determination of shape can either take place directly in the mouth, from a cast impression or from a model. During optical input of natural teeth directly in the oral cavity, the measurements are impaired by saliva, and other optical imperfections on the surface of the tooth, such as different shades of color, etc. The accuracy of inputting the three-dimensional shape is, therefore, sometimes too low, which can lead to the fit of the insert being poor. For these reasons, it is still preferable when using known techniques to carry out the measurement outside of the oral cavity. During measurement, it is often sufficient to determine the shape of the surface to which the restoration body is to be adapted. Under certain conditions, however, it is also desirable to measure adjacently and oppositely located teeth.
Accordingly, it is a primary object of the present invention to provide a method and apparatus for the remote determination of a three-dimensional shape of dental objects, such as teeth, casts of teeth and models of teeth.
Another object of the present invention is to provide a method and apparatus which can determined a three-dimensional shape more accurately and more cost effectively than the existing methods and apparatuses.
These and other objects of the present invention are fulfilled by providing a method for determining a three dimensional shape of a dental object comprising the steps of: providing a laser, a matrix of photo-detectors, and a controller; scanning a first narrow laser beam from the laser across a first surface area of the dental object; reflecting the first narrow laser beam away from the object; receiving a first scanning image of the reflected first narrow laser beam on the matrix of photo-detectors; determining first elevation profile data based upon the first scanning image relating to the first surface area; changing a relative angle between the laser, matrix of photo-detectors or dental object; scanning a second narrow laser beam from the laser across a second surface area of the dental object; reflecting the second narrow laser beam away from the object; receiving a second scanning image of the reflected second narrow laser beam on the matrix of photo-detectors; determining second elevation profile data based upon the second scanning image relating to the second surface area; and consolidating the first elevation profile data and the second elevation profile data to determine a three dimensional shape of the dental object.
Moreover, these and other objects of the present invention are fulfilled by providing an apparatus for determining a three dimensional shape of a dental object comprising: a transmission unit, including a laser, producing an essentially planar laser beam for illuminating an object with a narrow laser beam trace; a receiver unit arranged at a distance and to a side of said transmission unit, said receiver unit including a photo-detector matrix for receiving the laser beam reflected from the object; and a calculation unit connected to said photo-detector matrix calculating a three dimensional shape of the dental object based upon the reflected laser beam received by the photo-detector matrix.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.